MLA

Stieglitz, Alfred, 1864-1946. Letters. Box 82, folder 1669-1679. 1917 Mar-Oct. https://collections.library.yale.edu/catalog/2038297.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 82, folder 1669-1679"])(1917 Mar-Oct)[Letters]. https://collections.library.yale.edu/catalog/2038297.